The surprising evolution of bees

A world before bees

Before bees, the world bloomed differently, if it really bloomed at all.

Roughly 100 million years ago, Earth’s plant life was mostly green and wind-pollinated. Grasses, ferns and conifers dominated the landscape. Flowers were a new up-and-comer, having just recently emerged 30 million years prior, but they still mostly lacked color, scent and nectar. 

They weren’t trying to attract attention, because there was no one around to pay attention.

Then came bees.

Evolved from ancient predatory wasps, bees didn’t start as pollinators. They originally hunted insects. But at some point, perhaps drawn by the easy calories hidden away in pollen and nectar, some began visiting early flowering plants. That small dietary shift launched one of the most profound evolutionary exchanges in natural history.

Over millions of years, bees and flowering plants co-evolved. One couldn’t really move, but could offer rewards. The other could travel, but needed a destination. So flowers adapted to bees — and bees adapted to flowers. Beginning a slow, mutual transformation that would one day shape entire ecosystems.

Without that initial relationship, flowering plants might never have spread. Fruit trees, vegetables, wildflowers and the vast food webs built on them, might never have taken hold. 

A planet without bees wouldn’t just mean fewer colors (and fewer chances of getting stung). It would be a fundamentally different world.

From fearsome predators to pollen collectors

So why did early carnivorous wasps begin supplementing their diet with nectar and pollen?

For one, it was abundant. Flowering plants were beginning to bloom across the landscape, producing large amounts of pollen and nectar. For small insects, it was a great food source, rich, reliable, free from competition — a feast that neither fought back nor flew away.

This shift from carnivory to florivory was slow, but over time this dietary shift led to major adaptations that transformed these early wasps into the bees we recognize today.

They underwent morphological changes: hairs on the body became specialized pollen traps, eyes adapted to better see color, tongues lengthened to reach deep within floral structures and in some bees, pollen-carrying baskets formed on their legs. 

Behavioral changes emerged too. Nesting shifted from simple burrows to more complex constructions to store pollen. In some environments, social behaviors, such as cooperative foraging, division of labor and brood care became advantageous, allowing a colony to cover more territory, defend its nest and safely store the resource-rich pollen. 

The evolutionary arms race that made the planet bloom

But bees didn’t just use flowers; they helped guide their evolution too.

Plants that were more attractive to bees were pollinated more effectively than their neighbors, and passed on their genes. So natural selection favored traits that helped them stand out: bright colors (especially blues and purples, which bees see best), strong scents, UV-reflective guides, and sugar-rich nectar—all helped lure bees toward the plants. 

Bees, in turn, evolved behaviors and senses that honed in on those cues. Their vision adapted to detect specific wavelengths of light. Their hairs became sensitive to the electrostatic fields of flowers. Their brains (among the smartest of all insects) developed to remember foraging patterns, landmarks and locations.

As you might already know, this mutual feedback loop where one species shapes the evolution of another and vice versa, is called coevolution. And in the case of bees and flowering flora, it led to an explosion of diversity on both sides. The spread of flowering plants, now the most abundant plants on Earth, strongly coincided with the emergence of intentional pollinators, like bees. As flowers emerged, so did bees, and together they helped one another disseminate across the planet. 

Today, there are over 20,000 known bee species and more than 300,000 species of flowering plants, many of which rely heavily, sometimes exclusively, on insect pollination.

Bees helped create the colorful world we live in. One adapted not just to grow, but to be found.

Evolution in action: How specialization shaped bee diversity

As flowering plants diversified, bees faced a set of evolutionary choices. Would they become specialists, building their biology around one or a few types of flowers? Or would they evolve into generalists, able to forage a broader range of blooms?

Both strategies have since thrived, but they reflect very different evolutionary pressures. 

Monolectic bees: The single species specialist

Monolectic bees are the pinnacle of loyalty. These species evolved to collect pollen from a single plant species, and often can’t survive without it.

While this level of specialization isn’t common, it’s incredibly precise. One example is the globe mallow bee, which has evolved alongside, you guessed it, the globe mallow flower. Everything from the timing of its emergence to its body shape is tailored to this one specific plant. It even has specialized hairs that only effectively grip that pollen type.

Why would evolution lead a bee down such a narrow path? In many cases, it’s about efficiency. Specialization can reduce competition with other pollinators, especially in environments where a specific flower is abundant and blooms predictably. By fine-tuning every aspect of their foraging to a single species, monolectic bees can become extremely effective at what they do while avoiding competing with other species for resources.

But this isn’t without risk. If that plant fails to bloom due to drought, habitat loss or disease, the bee has no fallback. Specialization makes you an expert in efficiency, but it also makes you incredibly vulnerable to change. 

Oligolectic bees: The evolutionary Goldilocks  

Oligolectic bees, while still loyal, take a slightly broader approach. They collect pollen from a few closely related plant species, usually within the same family or genus.

One example is the southeastern blueberry bee, which specializes in the Ericaceae family, which includes cranberries, huckleberries and, you guessed it, blueberries. These bees have evolved buzz pollination, which uses intense bodily vibrations to dislodge pollen, allowing them to access the tightly packed pollen inside berry blossoms.

Oligolecty likely evolved in regions where certain plant families dominate an ecosystem, such as pine barrens or shrubland. Instead of adapting to one species, these bees evolved to exploit a group of structurally or chemically similar flowers. This offers more resilience than monolectic foraging while still maintaining the benefits of specialization.

It’s a kind of evolutionary middle ground, less fragile than extreme specialists, yet more efficient than broad generalists.

Polylectic bees: The adaptable generalists

At the other end of the spectrum are polylectic bees, generalists that collect pollen from a wide variety of plant species, sometimes dozens or even hundreds.

The common eastern bumblebee is one of the most successful and widespread examples of these bees. Its flexible foraging behavior, broad flower preferences and ability to thrive in various climates have helped it spread across much of North America.

In environments where floral abundance changes rapidly, due to weather, seasonal changes, wildfires or disturbances — being flexible gives these bees an edge. Generalists are also better suited for modern urban or fragmented habitats, where plant diversity is high but consistency and access is lower.

They may not be as efficient as a specialist, but their broad range of adaptations and ecological versatility makes them critical to both wild and agricultural plants.

Whether specialized or broadly adaptable, every bee species tells part of the same story of coevolution, mutualism and ecological connectivity. Their differences reveal not just how bees evolved, but why they matter today. Taken together, they show just how deeply the world has come to depend on these small, fascinating creatures.

An 100-million-year long story

From their unlikely beginnings as insect-hunting wasps to their role today as keystone pollinators, bees have reshaped life on Earth in ways few other animals can claim. Their evolutionary partnership with flowering plants didn’t just fill the world with color; it transformed ecosystems, shaped plant diversity, and laid the foundation for countless food webs (including our own).

The staggering variety of bee species we see today, nearly 4,000 species in North America alone, reflects millions of years of adaptation, survival and coevolution. Some evolved to thrive in the smallest of niches, while others became masters of flexibility in ever-changing environments. No matter the adaptations, bees show us a microcosm of just how complex, strange and fascinating our natural world can be. 

And as their world changes, with (relatively speaking) new threats from pesticides, climate change, habitat loss and disease, with a quarter of our native bee species in decline, it’s important now, more than ever, to understand the fascinating story of how these crucial pollinators first spread across our world. 

While they may be struggling today, the story of bees isn’t just about the past. It’s a story still unfolding, in every blooming flower you see, every wildflower dotted meadow you pass and every bite of food you take.

Bees have been buzzing for 100 million years. They’re older than grass, older than birds, older than even the continents we recognize today. 

So let’s keep these fascinating, vibrant pollinators around as long as we can. For their sake, as well as our own.